I've been doodling a few ideas for how the GUI may eventually look. Here's a rough one:
The idea is that you (the user) should have a large view of the environment, and be able to navigate freely (the controls will probably be similar to Maya's, which work pretty well for 3D navigation). You should also have small views of all of the smart cameras, as if you're in the control room of a news show (in the above sketch, these show up at the top of the screen. There will probably be a limit to the number of smart cameras you can have at once). Clicking on a camera should open a window with options specific to that camera, so you can give it commands or constraints which will override the default "intelligent" behavior.
I've been thinking a lot about how all of this can actually be exported, so the "virtual documentary" that I keep talking about can be watched later, and not just while the events are happening. One possibility would be for every camera to export its own footage as some sort of video file, so a user can watch any of them by themselves, or edit them together in Final Cut or Premiere or something.
But I really like the idea of editing the movie in real-time. While the individual cameras will be smart enough to cut to different angles, I think the user should be in charge of actually cutting between different cameras.
Basically, the user would be a "Video DJ." There's one camera window, let's call it the "master track," which is the one whose footage is actually exported when the program is closed. The master track is always linked to one camera, and shows the footage that it's capturing—in the GUI diagram above, the master track is the top window all the way to the left, and it's currently linked to camera 1.
By pressing a keyboard button (maybe the number keys would be tied to numbered cameras), the user changes which camera is being recorded on the master track. This way, while each individual camera is capturing a different event, the user can cut between them at will, like a DJ cutting between different records. There could even be different keyboard commands for different transitions, like fade-outs, wipes, dissolves, and so on. Or a user could pick some sort of default setting, like having the master track just alternate between cameras every couple of seconds.
Anyway, all of these recording things are just thoughts. The first version of the GUI will simply allow the user to navigate around and click on events, while a window will display a smart camera's view. DJ'ing will have to wait.